1. Field of the Invention
The invention relates to axial piston rotary power devices having one or more pistons disposed parallel to and displaced from an axis of rotation. More particularly, the invention relates to internal combustion engines, pumps, compressors, expanders, fluid driven motors, compressor driven internal combustion engines, and fluid driven compressors. It additionally relates to any such devices that differ in a simple structural modification of a central cylindrical stationary member, cam profile and end plate ports.
2. Background Information
This invention relates to rotary power devices of the type having a plurality of cylinders arranged around and parallel to a central axis of rotation in an equally-spaced relationship, and in which pistons disposed within the cylinders cooperate with a cam track to impart rotational motion to a rotor when the pistons reciprocate in their respective cylinders. Examples of rotary devices of the above type can be found in United States patent specifications such as U.S. Pat. No. 5,813,372 of Manthey; U.S. Pat. No. 4,287,858 of Anzalone; U.S. Pat. No. Re. 30,565 and U.S. Pat. No. 4,157,079 of Kristiansen; U.S. Pat. No. 5,209,190 of Paul; U.S. Pat. No. 5,103,778 of Usich, Jr.; U.S. Pat. No. 5,253,983 of Suzuki, et al.; U.S. Pat. No. 5,323,738 of Morse; U.S. Pat. No. 4,213,427 of Di Stefano; and U.S. Pat. No. 1,614,476 of Hutchinson. Although such power devices have been proven to be theoretically functional, they are characterized in some respects by complexities associated with the arrangements of cams and of intake and discharge means, which make them costly to manufacture, assemble, and maintain. Furthermore, the apparatus of the present invention represents one or more improvements over a device described in the inventor""s pending U.S. patent application Ser. No. 09/977,633, filed on Oct. 15, 2001, the disclosure of which is herein incorporated by reference.
An axial piston rotary power device of the invention comprises a stator portion and a rotor portion having a rotatable shaft extending along an axis of the device. The stator portion of the device comprises an external stator portion defining a generally cylindrical interior bounded by a back plate portion and a front plate portion that has a central throughhole within which the rotatable shaft is journaled. A middle portion of the external stator is preferably formed from a pair of diagonally-split mating elements. In addition, the stator comprises a cylindrical internal stator portion projecting from the back plate portion into the cylindrical interior along the axis of the device so as to define an annular space extending between the internal and external stator portions. The internal stator portion has a plurality of passageways within it, each of the passageways comprising a channel parallel to the axis and each of the channels communicating with at least one respective radially oriented port formed in the internal stator at a respective selected axial position. Yet another static portion of a preferred device is an axially undulating guide track surface that may comprise a surface protruding inwardly, by a predetermined amount, from the annular internal wall of the middle portion of the external stator of the device.
The rotor portion of the device comprises a cylindrical block having a medial annular cutout portion extending through its outer surface so as to form an annular recess. The block is fixedly attached to the shaft and rotatable within the annular space between the internal stator portion and the external stator portion and is arranged so that a protruding guide track surface attached to or forming a portion of the middle portion of the external stator fits into the annular cutout. This block has a central cylindrical bore adapted to receive the internal stator, and also includes a selected number of cylindrical cavities parallel to the axis of the device and spaced apart from that axis by a single selected radial distance. Each of the cylindrical cavities is divided into a pair of working cylinders axially separated from each other by a portion of the annular cutout. Each of these cylindrical cavities has a radially inwardly directed end opening adjacent each of its two ends. One of these end openings is associated with a working cylinder in the first set thereof and may communicate with the central cylindrical bore at a first selected axial position. The other end opening in each cylindrical cavity is associated with the associated working cylinder of the second set and may communicate with the central cylindrical bore at a second selected axial position. Alternatively, working cylinders of the first set may comprise respective end openings communicating with the central bore at one selected axial position, and working cylinders of the second set may comprise axial end openings communicating with passages formed in one of the end plates of the external stator.
It will be recognized that either working cylinder arrangement can be described in terms of two sets of working cylinders aligned parallel to the axis of the device, wherein each of the sets comprises a circular array and wherein each cylinder in one set is axially aligned with a respective one of the working cylinders in the other set.
In addition, the annular surface of the cutout portion of the cylindrical block may include an equal number of axial cam grooves extending between ones of each pair of working cylinders. In an operating configuration, each pair of axially opposed working cylinders slidably receives a respective piston assembly. Each of the piston assemblies comprises two opposed cylindrical piston heads fixedly coupled by a middle portion which preferably comprises a pair of axially spaced apart roller cam followers receiving the protruding cam guide. In addition, the middle portion of the piston assembly preferably includes a detachable cam pin follower slidably engaging the cam groove. All of the roller cam followers engage the undulating protruding guide surface so as to couple a rotary motion of the block to the reciprocating translational motions of the pistons. If the pistons are driven to and fro within the cylinders by known means such as the expansion of an explosive air-fuel charge, or by the introduction of a pressurized working fluid, the rotary power device of the invention can function as an internal combustion engine, a fluid-driven compressor, a compound internal combustion and compressor, a fluid-driven motor or expander device providing output shaft power. Conversely, if the block is rotated by the application of a torque to the input shaft, the rotary power device of the invention can function as a pump or compressor.
One embodiment of the present invention provides an improved spark ignition rotary internal combustion engine which operates in a four-cycle mode and which overcomes problems presently encountered in the class of rotary engine having pistons positioned parallel to each other around a common axis of rotation. Another embodiment of the present invention provides an improved rotary internal combustion engine which operates in a two-cycle mode and which overcomes problems presently encountered in the class of rotary engines having pistons positioned parallel to each other around a common axis of rotation.
Another feature of a preferred rotary power device of the invention is that it can be easily converted to a different type of rotary power device by a simple modification or replacement of a central stationary member, cam profile or front end plate. Thus, one can convert an internal combustion engine of the invention into a rotary power device that can act as any one of a pump, a compressor, a fluid-driven pump, a fluid-driven compressor, a fluid-driven motor and an internal combustion-driven compressor
A preferred embodiment of the invention provides a rotary power device having valveless ports.
A feature of some embodiments the invention is that they are light in weight, small in size and have a reduced part count when compared with prior art rotary power devices.
A benefit of some embodiments of the invention is that they provide a rotary power device that closely approximates continuous intake, compression, combustion and discharge processes.
Another benefit of some embodiments of the invention is that they provide a rotary power device characterized by reduced noise and vibration.
Although it is believed that the foregoing recital of features and advantages may be of use to one who is skilled in the art and who wishes to learn how to practice the invention, it will be recognized that the foregoing recital is not intended to list all of the features and advantages. Moreover, it may be noted that various embodiments of the invention may provide various combinations of the herein before recited features and advantages of the invention, and that less than all of the recited features and advantages may be provided by some embodiments.